The disclosure relates generally to lifting devices, and more particularly, to a triangular lift frame having load blocks for component loads such as a steam turbine component.
Currently, lifting a component that does not have evenly distributed weight and/or has non-symmetrical connection points, presents a number of challenges. One challenge is that the rigging arrangement may lead to damage of the component load. For example, FIG. 1 shows a three-legged bridle 10 coupled to eyelets 12 mounted directly on component 14, i.e., a steam turbine diaphragm half. As observed, each leg of the bridle 10 may rub against and damage an edge of component 14 if, for example, accurate crane operation is not implemented. One approach to minimize risk in this situation has been to reduce the size of the eyelet, but this is difficult to implement in the field. As shown in FIG. 2, where a swivel hoist ring 16 is used with a three-legged bridle, the ring may also impact an edge of component 14.
Another approach to address the above-identified challenge is to implement a triangular lift frame that includes frame members that are coupled by vertical, welded gussets. The gussets include connection points for hoist rings. This approach presents a number of challenges because the gussets, welds and frame members are all carrying the load of the component. In addition, since the gussets are simply vertically welded to the frame members, the load transmission to the frame members may include an amount of torsion on the frame members and/or shear on the welds. Application of this approach therefore can be limited.
In any conventional approach, damage to industrial components, such as turbine diaphragms, due to improper lifting can result in required repairs resulting in delivery delays and unnecessary costs. In the steam turbine setting, the costs can be extensive considering hundreds of steam turbine diaphragms may be handled each year during plant outages and repair activities in service shops. Similar damage and cost problems exist for other industries.